ObjectiveTo analyze the predictive value of the serum amyloid A/C-reactive protein ratio (SAA/CRP), lactate dehydrogenase (LDH), and chitinase-40 (YKL-40) combined with conventional influencing factors for the prognosis of children with refractory mycoplasmal pneumonia (RMPP).MethodsA retrospective study was conducted on 180 children with RMPP admitted to the First People's Hospital of Nanyang from January to December 2023, serving as study group, and 90 children with general mycoplasmal pneumonia (GMPP) as control group. The clinical data of the two groups, including age, gender, and serum levels of SAA/CRP, LDH, and YKL-40, were compared. On the day of admission, the disease severity of the children in study group was assessed and divided into mild (n=102) and severe (n=78) groups. After treatment, they were further categorized into poor prognosis (n=52) and good prognosis (n=128) groups based on the occurrence of adverse events. The levels of serum SAA/CRP, LDH, and YKL-40 were compared between mild-case and severe-case children in study group, as well as between children with good and poor prognosis. A binary logistic regression model was used to analyze the influencing factors for poor prognosis in children with RMPP. Receiver operating characteristic (ROC) curve was used to evaluate the predictive value of serum SAA/CRP, LDH, and YKL-40 for the prognosis of children with RMPP. Conventional influencing factors [disease severity, oxygen therapy duration, pneumonia severity index (PSI) score, and acute physiology and chronic health evaluation Ⅱ (APACHE Ⅱ) score] were used as the conventional prediction scheme, and the conventional prediction scheme combined with the levels of serum SAA/CRP, LDH, and YKL-40 was used as the new prediction scheme. The predictive values of the two prediction schemes for the prognosis of children with RMPP were compared.ResultsThe levels of serum SAA/CRP, LDH, and YKL-40 in study group were higher than those in control group (P<0.05), and the levels of serum SAA/CRP, LDH, and YKL-40 in children with severe RMPP were higher than those in children with mild RMPP (P<0.05). In study group, the proportion of children with pleural effusion, the proportion of severe-case disease severity, oxygen therapy duration, PSI score, APACHE Ⅱ score, and the levels of serum SAA/CRP, LDH, and YKL-40 in children with poor prognosis were higher than those in children with good prognosis (P<0.05). Binary logistic regression analysis showed that disease severity, oxygen therapy duration, PSI score, APACHE Ⅱ score, and the levels of serum SAA/CRP, LDH, and YKL-40 were all factors affecting poor prognosis in children with RMPP (P<0.05). The areas under the curves (AUCs) of serum SAA/CRP, LDH, and YKL-40 for predicting the prognosis of children with RMPP were 0.756, 0.749, and 0.734, respectively. The AUC of the new prediction scheme was 0.945, which was significantly higher than that of the conventional prediction scheme (AUC=0.859), with a statistically significant difference (P=0.011).ConclusionSerum SAA/CRP, LDH, and YKL-40 levels combined with the conventional prediction scheme have a high predictive efficacy for the prognosis of children with RMPP.

refractory mycoplasma pneumoniae pneumonia;serum amyloid A/C-reactive protein ratio;lactate dehydrogenase;chitin enzymes protein 40